1. Field of the Invention
The present invention relates to an edge enhancement process unit that carries out an edge enhancement process for an image signal generated by an imaging device.
2. Description of the Related Art
An edge enhancement process is carried out for an image signal generated by an imaging device comprised in an electric endoscope. The edge enhancement process is ordinarily carried out by calculating the remainder of a signal intensity of luminance signal or color difference signal for a focused pixel and surrounding pixels around the focused pixel, and by adding the remainder to the signal intensity for the focused pixel.
Incidentally, a wide-angle lens may be used for an imaging device, such as an imaging device comprised in an electric endoscope. Such a wide-angle lens distorts an optical image in the side. Such a distorted image is hidden by being colored with black.
When the above-described edge enhancement process is carried out for a pixel neighboring the black-colored pixel, a white line is displayed along the black colored area (see FIG. 8), or an artificial image is displayed. Such a white line or an artificial image is unsightly for a user.